The synthesis of cyclopentenones of type VIII ##STR3## wherein n is 5-7, preferably 6, and their use as key intermediates in the synthesis of prostaglandin analogs of pharmacological interest have been described in U.S. Pat. No. 4,254,285, which is incorporated herein by reference, as though fully set forth herein. The synthesis of cyclopentenones (VIII) as reported in U.S. Pat. No. 4,254,285, Flowsheet K involves the conversion of cyclopentenones of type IX ##STR4## wherein Z is --(CH.sub.2).sub.g --, wherein g is 5-7 to cyclopentenones of type VIII, wherein n is as above described. In the method of this patent conversion of the carboxylic acid moiety of IX into a hydroxymethylketo moiety employs either diazomethane or 1,1,2-tris-trimethylsiloxyethylene. (Dimethyl)-t-butylsilane is also employed.
In accordance with the method of the present invention cyclopentenones of type VIII are generated in one step by the acid-catalyzed deprotection and rearrangement of a protected .alpha.-hydroxymethylfuran which incorporates a protected hydroxymethylketo moiety.